Nature of Operations and Basis of Presentation - Estimated Fair Values of Assets Acquired as of Acquisition Date (Detail) - USD ($) $ in Thousands	Sep. 30, 2016	Dec. 31, 2015
Business Acquisition [Line Items]
Goodwill	$ 142,439	$ 126,145
ETTI [Member]
Business Acquisition [Line Items]
Property, plant and equipment	4,300
Intangible assets	2,900
Goodwill	10,700
Total assets acquired	$ 17,900